On 03/06/16 23:40, Alex Bennée wrote:
> diff --git a/cpus.c b/cpus.c
> index 1694ce9..12e04c9 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1208,9 +1208,29 @@ static int tcg_cpu_exec(CPUState *cpu)
> return ret;
> }
>
> +/* Single-threaded TCG
> + *
> + * In the single-threaded case each vCPU is simulated in turn. If
> + * there is more than a single vCPU we create a simple timer to kick
> + * the vCPU and ensure we don't get stuck in a tight loop in one vCPU.
> + * This is done explicitly rather than relying on side-effects
> + * elsewhere.
> + */
> +static void qemu_cpu_kick_no_halt(void);
> +#define TCG_KICK_FREQ (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + \
> + NANOSECONDS_PER_SECOND / 10)
Hmm, it doesn't look nice to wrap calculation of the next timeout in a
macro and name it '*_FREQ'. I think we'd better do like this:
#define TCG_KICK_PERIOD (NANOSECONDS_PER_SECOND / 10)
static inline int64_t qemu_tcg_next_kick(void)
{
return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + TCG_KICK_PERIOD;
}
and use it like this:
timer_mod(kick_timer, qemu_tcg_next_kick());
Kind regards,
Sergey
> +
> +static void kick_tcg_thread(void *opaque)
> +{
> + QEMUTimer *self = *(QEMUTimer **) opaque;
> + timer_mod(self, TCG_KICK_FREQ);
> + qemu_cpu_kick_no_halt();
> +}
> +
> static void *qemu_tcg_cpu_thread_fn(void *arg)
> {
> CPUState *cpu = arg;
> + QEMUTimer *kick_timer;
>
> rcu_register_thread();
>
> @@ -1234,6 +1254,13 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
> }
> }
>
> + /* Set to kick if we have to do more than one vCPU */
> + if (CPU_NEXT(first_cpu)) {
> + kick_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, kick_tcg_thread,
> + &kick_timer);
> + timer_mod(kick_timer, TCG_KICK_FREQ);
> + }
> +
> /* process any pending work */
> atomic_mb_set(&exit_request, 1);
>
